10.1021/ic501051q.s003 Paula Cucos Paula Cucos Floriana Tuna Floriana Tuna Lorenzo Sorace Lorenzo Sorace Iulia Matei Iulia Matei Catalin Maxim Catalin Maxim Sergiu Shova Sergiu Shova Ruxandra Gheorghe Ruxandra Gheorghe Andrea Caneschi Andrea Caneschi Mihaela Hillebrand Mihaela Hillebrand Marius Andruh Marius Andruh Magnetic and Luminescent Binuclear Double-Stranded Helicates American Chemical Society 2014 temperature dependence 55 K relaxation rate Dynamic susceptibility measurements evidence metal ions helicate Orbach mechanism EPR spectroscopy axis type anisotropy dc field Zn fluorescence quantum yields Co exhibits fluorescence emission tetrahedral geometry M 2L center cobalt ions helicand H 2L 2014-07-21 00:00:00 Dataset https://acs.figshare.com/articles/dataset/Magnetic_and_Luminescent_Binuclear_Double_Stranded_Helicates/2272807 Three new binuclear helicates, [M<sub>2</sub>L<sub>2</sub>]·3DMF (M = Co­(II), <b>1</b>, Zn­(II), <b>3</b>) and [Cu<sub>2</sub>L<sub>2</sub>]·DMF·0.4H<sub>2</sub>O (<b>2</b>), have been assembled using the helicand H<sub>2</sub>L that results from the 2:1 condensation reaction between <i>o</i>-vanillin and 4,4′-diaminodiphenyl ether. The metal ions within the binuclear helicates are tetracoordinated with a distorted tetrahedral geometry. Direct current magnetic characterization and EPR spectroscopy of the Co­(II) derivative point to an easy axis type anisotropy for both Co­(II) centers, with a separation of at least 55 K between the two doublets. Dynamic susceptibility measurements evidence slow relaxation of the magnetization in an applied dc field. Since the distance between the cobalt ions is quite large (11.59 Å), this is attributed in a first instance to the intrinsic properties of each Co­(II) center (single-ion magnet behavior). However, the temperature dependence of the relaxation rate and the absence of slow dynamics in the Zn­(II)-doped sample suggest that neither the simple Orbach mechanism nor Raman or direct processes can account for the relaxation, and collective phenomena have to be invoked for the observed behavior. Finally, due to the rigidization of the two organic ligands upon coordination, the pure zinc derivative exhibits fluorescence emission in solution, which was analyzed in terms of fluorescence quantum yields and lifetimes.